In the field of electrical cable couplers, it is necessary to protect the electrical contacts and insulation of the coupler sections against contamination by dust and moisture. The need for protection is especially critical when the coupler sections are disconnected in environments, e.g., coal mines, which contain an abundant supply of contaminants.
Typically, to provide the desired protection against dust and moisture, prior art cable couplers have included screw-on end caps which are chained to the housings of the coupler sections. Under typical operating conditions, the chains connecting the end caps to the coupler sections eventually become broken and the end caps are lost or misplaced. Since the screw-on end caps must be manually attached to the coupler sections, there has been a tendency for users to ignore the requirement of replacing the end caps when the coupler sections are disconnected so that the electrical contacts and insulation are unprotected even though the end caps are not lost or misplaced. As a result, the use of screw-on end caps has not provided a completely satisfactory protective cover arrangement for electrical cable couplers.
To overcome the disadvantages of manual screw-on end caps, it has been proposed to provide automatic protective cover arrangements which automatically operate when the coupler sections are disconnected to provide the desired protection against dust and moisture. Typically, the automatic arrangements have provided protective covers for the socket or female section of the cable coupler, but no protective cover has been provied for the plug or male section of the cable coupler. As a result, the electrical contacts and insulation of the plug or male section of the cable coupler have generally been unprotected against contamination by dust and moisture. See, for example, U.S. Pat. No. 3,525,068 disclosing an electrical connector wherein a tumbler member is rotatably mounted within the socket body for movement from an initial position covering the electrical contacts provided therein to a second position placing the plug contacts into electrical engagement with the socket contacts, and U.S. Pat. No. 3,982,804 disclosing an electrical connection device wherein the socket is provided with a rotatable safety disc which normally covers the socket contacts when the plug is disconnected and which rotates when the plug is engaged with the cover to allow the plug contacts to be inserted into the socket contacts.
Accordingly, it is a primary object of the present invention to provide an improved electrical cable coupler which incorporates an automatically operable protective cover arrangement on both of its coupler sections to protect its electrical contacts and insulation from contamination.
Another object of the invention is to provide an electrical cable coupler wherein plug and socket members are each provided with rotatable protective covers which normally cover the respective electrical contacts to provide protection against contamination when the plug and socket members are disconnected.
It is also an object of the invention to provide an electrical cable coupler comprising plug and socket members provided with rotatable protective covers which are adapted to interlock and rotate as a unit when the covers are placed in face-to-face engagement and the plug and socket members are twisted in opposite directions to allow the plug and socket contacts to be electrically engaged.
A further object of the invention is to provide an electrical cable coupler comprising plug and socket members provided with rotatable protective covers wherein at least one of the covers is inwardly slidable to allow the plug and socket contacts to be electrically engaged by axial movement of the plug and socket members together.
It is a further object of the invention to provide an electrical cable coupler comprising plug and socket members provided with rotatable protective covers which are normally biased into protective positions to prevent contamination of the electrical contacts and insulation when the plug and socket members are uncoupled.